Add Promise.sleep to std

CONTRIBUTING.md

@@ -350,6 +350,7 @@ Some tips:
 - Always use `@deprecated` when applicable.
 - Always use `@raise` when applicable.
 - Always provide a `@see` tag pointing to MDN for more information when available.
+- Format code samples in doc comments via `./cli/rescript-tools.js format-codeblocks <path-to-rescript-file>`
 
 See [Ocamldoc documentation](http://caml.inria.fr/pub/docs/manual-ocaml/ocamldoc.html#sec333) for more details.
 
@@ -389,6 +390,7 @@ Adding a new entry there requires re-running the analysis tests. Follow these st
 (If a `make` command fails, consider using the [DevContainer](#b-devcontainer).)
 
 Finally, add a line to [CHANGELOG.md](CHANGELOG.md), using the `#### :nail_care: Polish` section.
+
 ## Code structure
 
 The highlevel architecture is illustrated as below:

packages/@rescript/runtime/Stdlib_Promise.res

@@ -112,3 +112,8 @@ external any: array<t<'a>> => t<'a> = "any"
 external done: promise<'a> => unit = "%ignore"
 
 external ignore: promise<'a> => unit = "%ignore"
+
+let sleep = ms =>
+  make((resolve, _) => {
+    let _ = Stdlib_Global.setTimeout(resolve, ms)
+  })

packages/@rescript/runtime/Stdlib_Promise.resi

@@ -441,3 +441,18 @@ external done: promise<'a> => unit = "%ignore"
   without having to store or process it further.
 */
 external ignore: promise<'a> => unit = "%ignore"
+
+/**
+`sleep(ms)` creates a promise that resolves after `ms` milliseconds.
+
+## Examples
+
+```rescript
+Promise.sleep(1000)
+->Promise.thenResolve(() => {
+  Console.log("1 second has passed")
+})
+->Promise.ignore
+```
+*/
+let sleep: int => promise<unit>

packages/@rescript/runtime/lib/es6/Stdlib_Promise.js

@@ -6,7 +6,14 @@ function $$catch(promise, callback) {
   return promise.catch(err => callback(Primitive_exceptions.internalToException(err)));
 }
 
+function sleep(ms) {
+  return new Promise((resolve, param) => {
+    setTimeout(resolve, ms);
+  });
+}
+
 export {
   $$catch,
+  sleep,
 }
 /* No side effect */

packages/@rescript/runtime/lib/js/Stdlib_Promise.js

@@ -6,5 +6,12 @@ function $$catch(promise, callback) {
   return promise.catch(err => callback(Primitive_exceptions.internalToException(err)));
 }
 
+function sleep(ms) {
+  return new Promise((resolve, param) => {
+    setTimeout(resolve, ms);
+  });
+}
+
 exports.$$catch = $$catch;
+exports.sleep = sleep;
 /* No side effect */